Pneumatically-operated percussion-tool.



,mmm CHBISTIANSEN, or PINNEBERG, GEEMANY;

,PNEUMATICALLY-OPEBATED rnncUssIoN-roon Speciflcation of Letters Ptent.

' Patented May 22, 191%' Application filed October 26, 1916; sem No. 27,so. i

To all whom it may &mm; I

V Be it known that I, HEINRIH sEN, actizen of 'the German Empire,'resi-' dent at Pinneberg, in the Kingdom of Prussia," German Empire', have invented new and useful' Improvements Relating to Pneumatically-Operated Percussion Tools, of .which 'the following is aScilation.

This invention' `relates to pneumatically operatedpercus sion'- tools actuated byre-` ciprocating air-columns, such tools including percussion drills, pneumati`c hammers,'

. stamping 'tools for railways, and so forth.

A tool constructed. according to the"pr es-- In such tools areciprocating ,piston-haminer'b is driven ba ward and forward' in a cylinder ;m by connecting thet'spaces front and behind the' hammer-'piston b by' means of ports jo and d and suitablepiping to c'ylinder spaces in front 'of and behind' a power driven reciprocating piston or pistons. The, power-driven reciprocating piston and thehammier-piSton b operated by the air-columns, moving to and'fro' between these pistons, therefore' Carry out corresponding movements. On' the *forward movement the hammer-piston b strikes the tool e and transmits its kinetic energy by this impact. The tool eis guided in the' tool holder gwhich is mounted in' the neck of the cylinder' w. The tool e is provided with' a collar, e" which'during the forward' movement of the' tool, first moves freely I and then strikes against the front end of a spring z' of which the-resti' end is Secured, for example by being threaded ,on the neck of the cylinder. 'The spring i thus prevents the tool from being driven out in case the tool is not in contact with thework When the whole-ener v of the hammeriston b is expendedin't e accelerationoft e tool e, In order to prevent theham mer-pston from striking against` thecylmdercoverf at the end of its, returnfst'roke, the port. d

- opens into the cyli-nder 'at' d" some d stance from the cylinder covefj fi The' hammerpiston b closes the opein of the-;port d' during its return stro e.- The closed CHRISTIAN- ton Z against the coverji In 'the space. in front .of the hannnertpiston 'such a cushioning effect must not take place as the kinetic energy of the piston must be completely e utilized in the' impact and no' other resistj ance must be-opposed to the forward movement of the piston than that of the work upon 'which the tool is ;to operate. Consequently' the'spacein front of the hammerpiston must be continuously in communication with the 'spacein front of the power-4 driven air piston whichefl'ects the reciprocation of the air-columns. The opening c' of the port e must therefore be as near as According. to the present inventionthe i hammer-piston is' automatically stopped in sp'ite of the continuedoperation of the air p'ston'which produces the movements of the reciprocating air-columns,' as soon as .the tool sno longer pressed against the work, and the hammer-piston b automatically recom- 'mences its operation assoon as thetool e is again' pressed against the work.` For this 'purpose the port c leading to the front oylinder; space is provi'ded, 1n addition to the opening c' at the front end of the cylinder, with asecond opening 0 disposed somewhat to the rear. This opening c is disposed so far toward 'the real' that it is closed by the hammer-piston b whenthe piston has still aconsiderab'le portion' of its stroketocomplete,

' space behindthe piston thus forms an aircushon and prevents the impact of the pispossible to the frontend of 'the cylnder and must' not be closed by the hammerpiston during normal working. i 4

before it strikes the tool e. The air in front e of the piston 'b communicates therefore 'during the last part` of ,the stroke of the hammer-piston entirely through the opening c' with the space in front of the powerdriven air-piston (see Fig. 1). When the toole rests against the work, the said tool can only be driven forward a short distance,

and the hammer-piston b can only be impelled forward through an equally shortdistance and therefore does not expose the opening c?. If however the tool e does not rest against the work; then it can be driven by the piston b to the osition shown in Fig. 2. The iston b 'is t en impelled forward such a distance' that the opening c `is`uncovered. The tool holder gis provided with' a steel spring' rin 'h over which' the'cylindrical boring in t e front e'nd' of the hammer-piston b engages It isthenheld by the spring h in such a manner that the bufi'er action of the spring i can no longer move back the tool e and by means-of this the piston b. The reciprocating air-columns whose movements are produced by the piston of the power-driven machine are now no longer separated by the piston b but communicate directly with one another through the port 0, opening 0 the space behind the hammerpiston b, the opening d', the port d and the connecting piping. The hammer-pisten is therefore not operated although the powerdriven piston continues to reciprocate. r If '1. A pneumatic percussion implement comprising a cylinder closed at its rear end, a hammer-pisten within said cylinder, a tool and means for guiding it in the forward end of said cylinder, said cylinder having a port opening a short distance from the rear end thereof for the admission of fluid to drive the hammer-piston toward the tool and to produce an air-cushion on the return stroke of the hammer-piston, and a port having one opening in the cylinder at the front thereof and also another opening in the cylinder at a distance behind the front end of the cylinder slightly greater'than' the length of the hanmer-piston,` whereby the two cylinder ports are put into communication behind said piston, and the pisten is rendered inoperative whenever the tool is not pressed against the work so asto oppose 'a resistance to the free forward movement of said tool and the piston.

2. A pneumatic percussion implement comprising a cylinder closed at its rearend, a hammer-piston within said cylinder, a tool andmeans for guiding it in the forward end of said cylinder, said cylinder having a port opening a short distance from the rear end thereof for the admission of fluid to drive the hammer-pisten toward the tool, a port having one opening in the cylinder at the front thereof and also another opening 'in the cylinder at a distance behind the front'end of the cylinder slightly greater than the length of the hammer-piston, whereby the two cylinder ports are put into communication behind said piston, and the piston is rendered inoperative whenever the tool is not pressedagainst the work so as to oppose a resistance to the free forward movement of said tool and the pisten, spring means for preventing the ejection of the tool from the cylinder, and means for holding the hammer-piston in its forward inoperative position so long as the tool is not pressed into contact with the work.

3. A pneumatic percussion implement comprising a cylinder having means for the admission and outflow of the operating fluid, a tool guide mounted in the forward end of the cylinder, a tool mounted in said guide, a hammer-piston mounted for r`ec`procation in said cylinder, spring means on said guide for holding the pisten in its forward inoperative position when the tool is not pressed back by the work, and by-pass- 'ing means from one of the ports, said bypassing means being so arranged that the Operating fluid can pass through the cylinder without Operating the piston when the 'pisten is held in the inoperative position.

In witness whereof'I have hereunto set my .hand in presence of two witnesses.

HETNRICH CHRISTIANSEN. 

